From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Monnier Subject: =?UTF-8?B?YnVnIzIzOTE3OiBQbGVhc2UgY29uc2lkZXIgbWFraW5nIEJ1ZyAj?= =?UTF-8?B?MjM5MTcgYSBibG9ja2VyIGZvciAyNS4xICh3YXMgUmU6IG9yZy1jYXB0dXJl?= =?UTF-8?B?OiBDYXB0dXJlIHRlbXBsYXRlIOKAmGfigJk6IE1hdGNoIGRhdGEgY2xvYmJl?= =?UTF-8?B?cmVkIGJ5IGJ1ZmZlciBtb2RpZmljYXRpb24gaG9va3Mp?= Date: Tue, 19 Jul 2016 21:50:07 -0400 Message-ID: References: <87vb066ejv.fsf@linaro.org> <8360s67qcp.fsf@gnu.org> <87bn1yyaui.fsf@linaro.org> <87mvlhmv0x.fsf_-_@moondust.awandering> <837fcl5zs9.fsf@gnu.org> <87a8hgkwcb.fsf@linaro.org> <8360s42mcb.fsf@gnu.org> <87eg6rgmlg.fsf@gmail.com> <83lh0y24y6.fsf@gnu.org> <83eg6q1hbo.fsf@gnu.org> <83a8hd1vzi.fsf@gnu.org> <834m7l1u8u.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:43426) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPgfE-0008DO-Kt for emacs-orgmode@gnu.org; Tue, 19 Jul 2016 21:51:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bPgfC-0001Ek-MZ for emacs-orgmode@gnu.org; Tue, 19 Jul 2016 21:51:07 -0400 Sender: "Debbugs-submit" Resent-Message-ID: In-Reply-To: <834m7l1u8u.fsf@gnu.org> (Eli Zaretskii's message of "Tue, 19 Jul 2016 19:13:21 +0300") List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+geo-emacs-orgmode=m.gmane.org@gnu.org Sender: "Emacs-orgmode" To: Eli Zaretskii Cc: 23917@debbugs.gnu.org, rpluim@gmail.com, jwiegley@gmail.com, alex.bennee@linaro.org, nljlistbox2@gmail.com > Do we care that using save-match-data in every call to replace-match > might mean a performance hit? I do but: - to be honest, it's probably lost in the noise. - if we copy search_regs.start and search_regs.end with something like alloca+memcpy (instead of calling Fmatch_data), the cost should be even more lost in the noise. Especially if you consider that the current code already loops through the match-data to adjust it. - it's the best fix we've found so far. > If it will, then this will again punish > most of the users for the benefit of those few who (1) have > buffer-modification hooks, and (2) those hooks call save-match-data. I think the combination of 1 and 2 is actually pretty frequent. Stefan PS: I can think of one (theoretical) other/better way to fix this problem: move the match-data adjustment so it's done within replace_range before running the after-change-functions. I think this would be very satisfactory, since it would mean that the Elisp code would always see the valid match-data (whereas currently the after-change-functions get passed not-yet-adjusted match-data), so save-match-data wouldn't mess it up. But I fear this would require much larger changes (and might involve a heavier performance cost as well).